Fuel comprising an emulsion between water and a liquid hydrocarbon

ABSTRACT

Fuel made from an emulsion between water and a liquid hydrocarbon and polymeric surfactant, used to stabilize the emulsion, obtainable by (a) reacting (i) at least one polyolefin oligomer functionalized with at least one group deriving from a dicarboxylic acid, or a derivative thereof; and (ii) at least one polyoxylalkylene having linear oxyalkylene units, the polyoxyalkylene being linked to a long-chain alkyl group optionally containing at least one ethylenic unsaturation; and (b) reacting the product of step (a) with (ii) at least one nitrogen compound selected from monoamines, polyamines and quaternary ammonium hydroxides. The fuel has high stability over time, without forming carbonaceous deposits adhering to metal surfaces.

[0001] The present invention relates to a fuel comprising an emulsionbetween water and a liquid hydrocarbon, to a process for fueling acombustion apparatus, and to a polymeric surfactant used to stabilizesaid emulsion.

[0002] It is known that the combustion of liquid hydrocarbons, forexample for feeding internal combustion engines or for producing heat,leads to the formation of numerous pollutants, in particular soot,particulates, carbon monoxide (CO), nitrogen oxides (NOx), sulphuroxides (SOx), and non-combusted hydrocarbons, which cause a remarkableatmospheric pollution.

[0003] It is also known that the addition of controlled amounts of waterto a fuel can significantly reduce the production of pollutants. It isbelieved that this effect is the result of various phenomena arisingfrom the presence of water in the combustion zone. For example, thelowering of the peak combustion temperature by water reduces theemission of nitrogen oxides (NOx), the formation of which is promoted byhigh temperatures. In addition, the instantaneous vaporization of thewater droplets promotes better dispersion of the fuel in the combustionchamber, thereby significantly reducing the formation of soot,particulates and CO. These phenomena take place without adverselyaffecting the yield for the combustion process.

[0004] Several solution have been proposed in attempts to add water toliquid fuel at the time of use, that is to say just before the fuel isinjected into the combustion chamber, or directly into the chamberitself. However, these solutions require modifications to be made to thestructure of the combustion apparatus and are not capable of achievingoptimum dispersion of the water in the fuel, which is an essentialrequisite for obtaining a significant reduction in pollutants withoutcompromising the calorific yield for the process.

[0005] Thus, the most promising and numerous efforts made hitherto weredirected towards the formulation of emulsions between liquidhydrocarbons and water in the presence of emulsifiers (surfactants) forthe purpose of uniformly dispersing the water in the hydrocarbon phasein the form of droplets of the smallest possible size.

[0006] For example, European Patent Application EP-A-475,620 describesmicroemulsions of a diesel fuel with water, which contain a cetaneimprover and an emulsifying system comprising a hydrophilic surfactantand a lipophilic surfactant. These surfactants are selected fromethoxylated C₁₂-C₁₈ alkylammonium salts of a C₉-C₂₄ carboxylic orsulphonic acid: the hydrophilic surfactant contains at least sixethylene oxide units, while the lipophilic surfactant contains less thansix ethylene oxide units.

[0007] European Patent Application EP-A-630,398 describes a fuel in theform of an emulsion consisting of a hydrocarbon fuel, from 3 to 35% byweight of water and at least 0.1% by weight of an emulsifying systemconsisting of a sorbitan oleate, a polyalkylene glycol and anethoxylated alkylphenol.

[0008] International Patent Application WO 97/34969 describes anemulsion between water and a hydrocarbon, for example a diesel fuel.This emulsion is stabilized by adding an emulsifier consisting of asorbitan sesquioleate, a polyethylene glycol monooleate and anethoxylated nonylphenol. This emulsifier has an overall HLB(hydrophilic-lipophilic balance) value of from 6 to 8.

[0009] A process for producing a stabilized emulsion of a liquid fueland water is described in European Patent Application EP-A-812,615. Thisprocess involves preparing a first emulsion by mixing the fuel, thewater and a surfactant, and subsequently mixing the emulsion thusobtained with more water to give the final emulsion. The emulsion isstabilized using a hydrophilic surfactant or a lipophilic surfactant, ora mixture thereof. Lipophilic surfactants which can be used are fattyacid esters of sorbitol, for example sorbitan monooleate, whilehydrophilic surfactants which are suitable for this purpose are fattyacid esters of sorbitol containing a polyoxyalkylene chain, for examplepolyoxyethylene sorbitan trioleate. Further stabilization of theemulsion can be obtained by adding ethylene glycol or a polyethyleneglycol.

[0010] International Patent Application WO 92/19701 describes a processfor reducing the emission of NOx from a gas turbine, in which anemulsion of water with a diesel fuel is used. The emulsion is stabilizedby adding an emulsifier selected from: alkanolamides obtained bycondensing an alkylamine or hydroxyalkylamine with a fatty acid; andethoxylated alkylphenols. The emulsifier preferably has an HLB value ofless than or equal to 8. Physical stabilizers such as waxes, cellulosederivatives or resins can be added to improve the stability. Asdescribed in patent application WO 93/07238, the above emulsion can befurther stabilized by adding a difunctional block polymer with a primaryhydroxyl end group, in particular a copolymer containing propyleneoxide/ethylene oxide blocks.

[0011] International Patent Application WO 00/15740 describes anemulsified water-blended fuel composition comprising: (A) a hydrocarbonboiling in the gasoline or diesel range; (B) water; (C) a minoremulsifying amount of at least one fuel-soluble salt made by reacting(C) (I) at least one acylating agent having about 16 to 500 carbon atomswith (C) (II) ammonia and/or at least one amine; and (D) about 0.001 toabout 15% by weight of the water-blended fuel composition of a watersoluble, ashless, halogen-, boron-, and phosphorus-free, amine salt,distinct from component (C). The acylating agent (C) (I) includescarboxylic acids and their reactive equivalents such as acid halides,anhydrides, and esters, including partial esters and triglycerides.

[0012] On the basis of the Applicant's experience, the chances ofsuccess in the use of fuels in the form of an emulsion between water anda liquid hydrocarbon are mainly associated with the possibility ofreplacing a conventional liquid fuel with an emulsified fuel without theneed for any structural changes to the combustion apparatus and withoutadversely affecting the correct functioning of this apparatus.

[0013] In particular, the fuel in the emulsion form requires highstability over time in a broad temperature range (for example for atleast three months under normal storage conditions, i.e. from −20° C. to+50° C.), so as to avoid, during residence in tanks, the formation of awater-rich phase which tends to become deposited at the bottom of thetank. Feeding this aqueous phase into the combustion chamber would bringabout a considerable impairment in the performance level of the engine,or even permanent damage thereto.

[0014] In addition, the Applicant has found that the addition ofemulsifiers to improve the stability of the emulsion can lead, duringcombustion, to the formation of carbonaceous deposits which adhere tothe internal surface of the combustion chamber and to the injectors.This phenomenon can adversely affect the running of the engine, as aresult of which frequent maintenance is necessary to remove thesedeposits.

[0015] The Applicant has now found that fuels comprising an emulsionbetween water and a liquid hydrocarbon can be produced using a polymersurfactant as defined below as emulsifier. The fuel thus obtaineddisplays high stability over time in a broad temperature range, withoutforming carbonaceous deposits adhering to the metal surfaces.

[0016] In a first aspect, the present invention thus relates to a fuelcomprising an emulsion between water and a liquid hydrocarbon, saidemulsion being stabilized by at least one emulsifier, characterized inthat the said emulsifier comprises a polymeric surfactant obtainable by:

[0017] (a) reacting (i) at least one polyolefin oligomer functionalizedwith at least one group deriving from a dicarboxylic acid, or aderivative thereof; and (ii) at least one polyoxyalkylene comprisinglinear oxyalkylene units, said polyoxyalkylene being linked to along-chain alkyl group optionally containing at least one ethylenicunsaturation; and

[0018] (b) reacting the product of step (a) with (iii) at least onenitrogen compound selected from: monoamines, polyamines and quaternaryammonium hydroxides.

[0019] In a further aspect, the present invention relates to a processfor fueling a combustion apparatus comprising at least one combustionchamber, comprising: feeding a fuel to said at least one combustionchamber; igniting said fuel in said at least one combustion chamber;wherein said fuel comprises an emulsion between water and a liquidhydrocarbon as described above.

[0020] Preferably, said combustion apparatus is an internal combustionengine.

[0021] According to a further aspect, the present invention relates to apolymeric surfactant obtainable by:

[0022] (a) reacting (i) at least one polyolefin oligomer functionalizedwith at least one group deriving from a dicarboxylic acid, or aderivative thereof; and (ii) at least one polyoxyalkylene comprisinglinear oxyalkylene units, said polyoxyalkylene being linked to along-chain alkyl group optionally containing at least one ethylenicunsaturation; and

[0023] (b) reacting the product of step (a) with (iii) at least onenitrogen compound selected from: monoamines, polyamines and quaternaryammonium hydroxides.

[0024] Preferably, the polyolefin oligomer has an average molecularweight of from 300 to 10,000, preferably from 500 to 5,000.

[0025] The polyolefin oligomer is generally obtained byhomopolymerization or copolymerization of at least one olefin containingfrom 2 to 16 carbon atoms, selected, for example, from:

[0026] α-olefins, i.e. olefins in which the double bond is in theterminal position, such as: ethylene, propylene, 1-butene, isobutene,4-methyl-1-pentene, 1-hexene, 1-octene, 2-methyl-1-heptene and the like;

[0027] internal monoolefins, i.e. olefins in which the double bond isnot in a terminal position, such as: 2-butene, 3-pentene, 4-octene andthe like.

[0028] The said olefins can moreover be copolymerized with otherhydrocarbons containing at least one ethylenic unsaturation, such asmonovinylarenes (for example styrene, p-methylstyrene and the like) orconjugated dienes (for example 1,3-butadiene, isoprene, 1,3-hexadieneand the like).

[0029] Preferably, the polyolefin oligomer derives from thepolymerization of mixtures of olefins containing 4 carbon atoms,generally containing from 35 to 75% by weight of 1-butene and from 30 to60% by weight of isobutene, in the presence of a Lewis acid as catalyst,for example aluminium trichloride or boron trifluoride. Thesepolymerization products are generally known as “polyisobutenes” sincethey mainly contain isobutene repeating units of formula:

[0030] The amount of isobutene units is usually not less than 80 mol %.

[0031] The polyoxyalkylene comprises linear oxyalkylene units whichimpart hydrophilic properties, in particular units of formula —CH₂CH₂O—,—CH₂CH₂CH₂O— or —CH₂CH₂CH₂CH₂O—, or mixtures thereof.

[0032] The number of linear oxyalkylene units is predetermined mainly asa function of the nature and length of the lipophilic portions presentin the polymeric surfactant, in particular of the polyolefin oligomerand the long-chain alkyl group.

[0033] Preferably, the polyoxyalkylene is a polyoxy-ethylene containingfrom 2 to 40, preferably from 5 to 20, oxyethylene units of formula—CH₂CH₂O—.

[0034] Alternatively, the polyoxyalkylene is a copolymer containing from2 to 30, preferably from 5 to 15, oxyethylene units of formula—CH₂CH₂O—, and not more than 12, preferably from 1 to 10, branchedoxyethylene units of formula:

[0035] wherein R is an alkyl containing from 1 to 3 carbon atoms.Preferably, R is methyl.

[0036] In the case of copolymers, the oxyalkylene units are distributedalong the chain randomly, in blocks or alternately. The number ofoxyalkylene units is expressed as the average number of units per chain.

[0037] The polyoxyalkylene is linked to a long-chain alkyl group. Thisalkyl group, of linear or branched structure, optionally containing atleast one ethylenic unsaturation, generally contains from 8 to 24 carbonatoms.

[0038] The link between the polyoxyalkylene and the long-chain alkylgroup is preferably made by an ester group or an ether group, and can beobtained by:

[0039] (A) condensing a polyoxyalkylene (polyalkylene glycol) with afatty acid or a derivative thereof, in particular an ester, withformation of the corresponding polyoxyalkylene monoester;

[0040] (B) esterification of a fatty alcohol with an alkylene oxide, inparticular with ethylene oxide or mixtures of ethylene oxide andpropylene oxide.

[0041] Examples of fatty acids which can be used in reaction (A) are:myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucicacid, ricinoleic acid, linoleic acid, linolenic acid, arachidonic acid,lauric acid, myristic acid, palmitic acid, stearic acid, behenic acidand the like, or mixtures thereof.

[0042] Examples of fatty alcohols which can be used in reaction (B) are:octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetylalcohol, octadecyl alcohol, oleyl alcohol, linoleyl alcohol, linolenylalcohol and the like, or mixtures thereof.

[0043] The polyolefin oligomer is functionalized by reaction with adicarboxylic acid, or a derivative thereof. In particular, thefunctionalization can be carried out by:

[0044] (i) concerted reaction of “ene” type between the polyolefinoligomer containing at least one ethylenic unsaturation and adicarboxylic acid derivative containing an ethylenic unsaturation;

[0045] (ii) anionic condensation reaction between the polyolefinoligomer functionalized with a leaving group (for example a halogen atomor a tosyl or mesyl group) and a saturated dicarboxylic acid derivative.

[0046] In both cases, acyl halides (preferably chlorides or bromides),C₁-C₄ esters or, preferably, anhydrides can be used as dicarboxylic acidderivatives.

[0047] The dicarboxylic acid containing an ethylenic unsaturation can beselected, for example, from: maleic acid, fumaric acid, citraconic acid,itaconic acid and the like, or mixtures thereof.

[0048] The saturated dicarboxylic acid can be selected, for example,from: malonic acid, succinic acid, glutaric acid, adipic acid,2-hexene-1,6-dioic acid, azelaic acid and the like, or mixtures thereof.

[0049] Preferably, the functionalized polyolefin oligomer derives fromthe reaction between maleic anhydride and a polyisobutene containing notless than 65 mol %, preferably not less than 80 mol %, of exo doublebonds, i.e. vinylidene groups of formula:

[0050] Polyisobutenes of this type are available, for example, under thebrand names Ultravis® (BP Amoco Chemicals) and Glissopal® (BASF).

[0051] Further details regarding the preparation of polyolefin oligomersfunctionalized as described above are given, for example, in U.S. Pat.Nos. 4,152,499 and 5,567,344.

[0052] The condensation reaction of step (a) between the functionalizedpolyolefin oligomer and the polyoxyalkylene bonded to a long-chain alkylgroup can be carried out in bulk or in the presence of an organicsolvent. Preferably, for the purpose of helping to remove the waterderiving from the condensation, the organic solvent is selected fromthose which form an azeotrope with water, for example toluene or xylene,or mixtures thereof. The condensation reaction can be carried out at atemperature which is generally not greater than 200° C. When an organicsolvent is used, the reaction temperature is usually not greater thanthe boiling point of this solvent. The reaction time can vary within awide range, generally from 3 to 24 hours.

[0053] As to step (b), it is carried out by reacting the product of step(a) with (iii) at least one nitrogen compound selected from: monoamines,polyamines and quaternary ammonium hydroxides.

[0054] The monoamines have only one amine functionality, and can beprimary, secondary or tertiary amines of formula:

[0055] wherein R1, R2 and R2, equal or different from each other, areselected from: hydrogen; C1-C24 hydrocarbyl group, otionally substitutedwith at least one group selected from hydroxy and C1-C4 alkoxy; R1 andR2 may be linked to form a nitrogen-containing aliphatic heterocyclicring, optionally containing at least one additional heteroatom (e.g.nitrogen and/or oxygen); with the proviso that at least one of R1, R2and R3 is different from hydrogen.

[0056] The hydrocarbyl group may be an aliphatic, cycloaliphatic,aromatic and/or heterocyclic group, linear or branched, saturated orunsaturated.

[0057] Specific examples of aliphatic monoamines include:trimethylamine, ethylamine, diethylamine, triethylamine, tripropylamine,n-butylamine, di-n-butylamine, tributylamine, methyldiethylamine,ethyldimethylamine, dimethylpropylamine, dimethylhexylamine,dimethyloctylamine, allylamine, isobutylamine, dimethylpentylamine,cocoamine, stearylamine, laurylamine, methyllaurylamine, oleylamine,N-methyloctylamine, dodecylamine, octadecylamine, or mixtures thereof.

[0058] Specific examples of cycloaliphatic monoamines include:cyclohexylamine, cyclopentylamine, cyclohexenyl-amine,cyclopentenylamine, N-ethyl-cyclohexylamine, dicyclohexylamine, ormixtures thereof.

[0059] Specific examples of hydroxyl-substituted amines (known also ashydroxyamines or alkanolamines) includes: ethanolamine, diethanolamine,ethylethanolamine, dimethylethanolamine, diethylethanolamine,di-(3-hydroxypropyl)amine, N-(3-hydroxybutyl)amine,N-(4-hydroxybutyl)amine, N,N-di-(2-hydroxypropyl)amine,N-(2-hydroxyethyl)morpholine, N-(2-hydroxylethyl)-cyclohexylamine,N-3-hydroxyl-cyclopentylamine, N-(hydroxyethyl)piperazine, or mixturesthereof.

[0060] Specific examples of aromatic monoamines includes:phenylethylamine, benzyldimethylamine, or mixtures thereof.

[0061] The polyamines may be aliphatic or cycloaliphatic compounds.Particularly preferred are alkylene polyamines of formula:

[0062] wherein:

[0063] n is from 1 to 10, preferably from 2 to 7;

[0064] R4, R5 and R6, equal or different from each other, are selectedfrom: hydrogen, alkyl or hydroxy-substituted alkyl group having from 1to 30 carbon atoms, with the proviso that at least one of R4 and R5 andat least one of R6 is hydrogen;

[0065] R7 is an alkylene group having from 1 to 18, preferably from 2 to6, carbon atoms.

[0066] Specific examples of polyamines includes: methylene polyamines,ethylene polyamines, butylene polyamines, propylene polyamines,pentylene polyamines, ethylene diamine, triethylene tetramine, propylenediamine, trimethylene diamine, tripropylene tetramine, tetraethylenepentamine, hexaethylene heptamine, pentaethylene hexamine, or mixturesthereof.

[0067] The quaternary ammonium hydroxides can be represented by thefollowing formula:

[0068] wherein:

[0069] R8, R9, R10 and R11, equal or different from each other, areselected from: C1-C24 hydrocarbyl group, otionally substituted with atleast one group selected from hydroxy and C1-C4 alkoxy; R8 and R9 may belinked to form a nitrogen-containing aliphatic heterocyclic ring,optionally containing at least one additional heteroatom (e.g. nitrogenand/or oxygen).

[0070] The hydrocarbyl group may be an aliphatic, cycloaliphatic,aromatic and/or heterocyclic group, linear or branched, saturated orunsaturated.

[0071] Specific examples of quaternary ammonium hydroxides include:tetramethylammonium hydroxide, tetraethylammonium hydroxide,tetrapropylanmonium hydroxide, tetrabutylammonium hydroxide,benzyltrimethyl-ammonium hydroxide, capryltrimethylammonium hydroxide,oleyltrimethylammonium hydroxide, hydroxyethyltributyl-ammoniumhydroxide, methoxyethyltributylammonium hydroxide, or mixtures thereof.

[0072] The reaction of step (b) can be carried out by mixing thereactants in bulk or in the presence of an inert organic solvent, e.g.xylene or toluene. The reaction temperature may vary within a widerange, usually from about 20° C. to about 180° C. The reactiontemperature is usually not greater than the boiling point of thenitrogen compound (iii) and, when an organic solvent is used, notgreater than the boiling point of the solvent. The reaction time canvary within a wide range, generally from 0.5 to 5 hours.

[0073] The product resulting from the reaction step (b) includes acarboxylate ammonium salt or an amide, or a mixture thereof, whichderive from the reaction of the nitrogen compound (iii) with theresidual carboxylic groups which are present in the product of step (a).The yield of salt and/or amide mainly depends on the specific reactantsand on the reaction conditions, particularly the reaction temperatureand time.

[0074] The equivalent ratio between the product of step (a) and thenitrogen compound (iii) may be varied over a wide range. Generally, theequivalent ratio may vary from 0.5 to 4, a ratio of about 1 beingpreferred. The number of equivalents for the product of step (a)corresponds to the number of residual carboxylic groups, and may bedetermined according to known techniques, e.g. by acid number (usuallyexpressed as mg KOH/g of product). The number of equivalents for thenitrogen compound (iii) is the molecular weight of the compound (iii)divided by the total number of basic nitrogen atoms present in themolecule.

[0075] The amount of polymeric surfactant to be used in the fuelaccording to the present invention is predetermined mainly as a functionof the amount of water to be emulsified and the type of liquidhydrocarbon used. Preferably, the polymeric surfactant as defined aboveis present in the fuel in an amount of from 0.1 to 5% by weight,preferably from 0.5 to 3% by weight, relative to the total weight of thefuel.

[0076] It should be noted that the polymeric surfactant as defined aboveis capable of effectively stabilizing the emulsion over a broadtemperature range without the addition of further emulsifiers. However,this is not to exclude the possibility of adding other products whichmay in some way modify the stability of the emulsion, in particularother emulsifiers known in the art.

[0077] The type of emulsion obtainable by using the polymeric surfactantas defined above is generally of the water-in-oil type, wherein thewater droplets are dispersed in the continuous hydrocarbon phase. It isbelieved that this type of emulsion ensures maximum efficiency in thereduction of pollutants on account of the water present during thecombustion phase.

[0078] The fuel according to the present invention includes a liquidhydrocarbon, generally deriving from the distillation of petroleum andconsisting essentially of mixtures of aliphatic, naphthenic, olefinicand/or aromatic hydrocarbons. The liquid hydrocarbon generally has aviscosity at 40° C. of from 1 to 53 cSt, and a density at 15° C. of from0.75 to 1.1 kg/dm³, and can be selected, for example, from: gas oils foruse as automotive fuels or for production of heat, fuel oils, kerosenes,aviation fuels (Jet Fuels).

[0079] The amount of water to be emulsified with the liquid hydrocarbonis determined so as to obtain the desired reduction in pollutantswithout, however, impairing the calorific yield for the combustionprocess. This amount is generally from 3 to 40% by weight, preferablyfrom 7 to 20% by weight, relative to the total weight of the fuel. Thewater used can be of any type, for example industrial or domestic mainswater. However, it is preferred to use demineralized or deionized water,in order to avoid the formation of mineral deposits on the internalsurface of the combustion chamber and/or on the injectors.

[0080] The fuel according to the present invention can contain otheradditives, whose nature and amount depend on the specific use for whichthe fuel is intended. These additives can be selected, for example,from: cetane improvers, corrosion inhibitors, lubricants, biocides,antifoaming agents, antifreezes, and mixtures thereof.

[0081] In particular, the cetane improvers are products which improvethe detonating properties of the fuel, and are generally selected fromnitrates, nitrites and peroxides of the organic or inorganic type, whichare soluble in the aqueous phase or, preferably, soluble in thehydrocarbon phase, such as organic nitrates (see for example patentsEP-475,620 and U.S. Pat. No. 5,669,938). Of preferred use are alkyl orcycloalkyl nitrates containing up to 10 carbon atoms, such as: ethylnitrate, amyl nitrates, n-hexyl nitrate, 2-ethylhexyl nitrate, n-decylnitrate, cyclohexyl nitrate and the like, or mixtures thereof.

[0082] The biocides can be selected from those known in the art, such asmorpholine derivatives, isothiazolin-3-one derivatives,tris(hydroxymethyl)-nitromethane, formaldehyde, oxazolidines, ormixtures thereof.

[0083] The fuel according to the present invention can also include analcohol, which, by lowering the freezing point of the aqueous phase,serves mainly as an antifreeze. Alcohols which are suitable for thispurpose are, for example: methanol, ethanol, isopropanol and glycols, ormixtures thereof. The amount of alcohol is generally from 0.5 to 8% byweight, preferably from 1 to 4% by weight, relative to the total weightof the fuel.

[0084] The fuel according to the present invention is generally preparedby mixing the components using an emulsifying device known in the art,in which the formation of the emulsion can result from a mechanical-typeaction exerted by moving parts, or from passing the components to beemulsified into mixing devices of static type, or alternatively from acombined mechanical and static action. The emulsion is formed by feedingthe aqueous phase and the hydrocarbon phase, optionally premixed, intothe emulsifying device. The emulsifier and the other additives which maybe present can be introduced separately or, preferably, premixed eitherin the aqueous phase or in the hydrocarbon phase depending on theirsolubility properties. Preferably, the polymeric surfactant is premixedin the hydrocarbon phase.

[0085] The present invention will now be further illustrated by means ofsome working examples.

EXAMPLE 1

[0086] A. Preparation of Polyethylene Glycol Monoester (PEG-Monoester).

[0087] 300 g of an oleic acid/linoleic acid mixture in a 60/40 weightratio and 400 g of polyethylene glycol (PEG) (molecular weight (MW): 400g/mol) were mixed together in a reactor. 3.5 g of methanesulphonic acidas condensation catalyst and 340 ml of toluene as diluent (forming anazeotrope with H₂O) were added under stirring. The mixture was heatedgradually to 140° C. for a total time of about 5 hours, withdistillation and separation of the H₂O/toluene azeotrope. After furtherheating at 160° C. for 2 hours with distillation of the residualtoluene, the resulting product was degassed under vacuum for about 2hours at 140° C. The residual acidity was 4.5 mg of KOH per gram ofproduct.

[0088] B. Synthesis of the Polyisobutene Derivative by Reaction WithMaleic Anhydride.

[0089] 95 g of polyisobutene (PIB) (average MW: 950 g/mol) with an exodouble bond content ≧90% (Ultravis® 10 from BP Amoco Chemicals), 9.4 gof maleic anhydride and 37 ml of xylene were loaded into a 500 mlTeflon® autoclave. After degassing with nitrogen, the autoclave washeated to a temperature of 190° C. and kept at this temperature for atotal of 22 hours. At the end of the reaction, the autoclave was cooledto 70° C. and degassed under vacuum for about 2 hours. The product thusobtained (101 g), a viscous yellow liquid, had a polyisobuteneconversion yield equal to about 43% (determined by chromatography onsilica using hexane as eluant), a maleic anhydride residual contentlower than 0.2% wt, and an anhydride number (number of moles of bondedanhydride per 100 g of product) (determined by quantitative infraredspectroscopic analysis, based on the absorption peak at 1760 cm⁻¹) of0.052.

[0090] C. Synthesis of the intermediate ester (Step (a)).

[0091] The PIB functionalized with maleic anhydride obtained fromreaction B (52.6 g) was loaded into a reactor and heated to about 50°C., followed by addition, with stirring, of xylene (5 g) and thePEG-monoester obtained from reaction A (75 g). The solution obtained washeated at 140° C. for 1 hour. The temperature was then maintained at180° C. for 10 hours, with distillation and separation of the H₂O/xyleneazeotrope. The product thus obtained, a slightly brown-coloured viscousliquid, had a residual acidity of 5.1 mg of KOH per gram of product.

[0092] D. Synthesis of the polymeric surfactant (Step (b)).

[0093] D1. The product obtained in Step C was reacted with 1.45 g (=1equivalent) of diethanolamine by stirring for 1 hour at 30° C. Theresulting polymeric surfactant was a slightly brown viscous liquid, witha residual acidity of about 0.3 mg of KOH per gram of product.

[0094] D2. The product obtained in Step C was reacted with 1.45 g (=1equivalent) of diethanolamine by stirring for 4 hour at 140° C. whilestripping water under vacuum. The resulting polymeric surfactant was aslightly brown viscous liquid, with a residual acidity of about 0.3 mgof KOH per gram of product.

[0095] D3. The product obtained in Step C was reacted with 5.55 g (=1equivalent) of a 40% by weight aqueous solution ofbenzyltrimethylammonium hydroxide by stirring for 1 hour at 30° C. Theresulting polymeric surfactant was a slightly brown viscous liquid, witha residual acidity of less than 0.1 mg of KOH per gram of product.

EXAMPLE 2

[0096] 1000 g of an emulsion between diesel fuel and water were preparedusing the product of reaction D1 as emulsifier.

[0097] 18.87 g of the emulsifier obtained in Example 1-D1 were added to865 g of automotive diesel fuel of EN590 type, to which 0.565 g of2-ethylhexyl nitrate (cetane improver) had been added beforehand. Themixture was subjected to the action of a high shear mixer for a fewminutes, followed by addition of 115.00 g of water to which 0.565 g of abactericide (isothiazolin-3-one derivative) had been added beforehand.The emulsifier was then switched to the maximum stirring speed for about3 minutes. An emulsion having the composition below was thus obtained:diesel fuel 86.5% by weight water 11.5% ″ emulsifier 1.887% ″ cetaneimprover 0.0565% ″ bactericide 0.0565% ″

EXAMPLE 3

[0098] 1000 g of an emulsion between diesel fuel and water were preparedby following the same procedure of Example 2, except that as emulsifierthe product of Example 1-D2 was used.

EXAMPLE 4

[0099] 1000 g of an emulsion between diesel fuel and water were preparedby following the same procedure of Example 2, except that as emulsifierthe product of Example 1-D3 was used.

EXAMPLE 5 (Comparative)

[0100] 1000 g of emulsion were prepared according to the same procedureas that described in Example 2, the only difference being the use,instead of the emulsifier of Example 1, of 18.87 g of a surfactantmixture consisting of 87% by weight of sorbitan monooleate, 3% by weightof sorbitan trioleate and 10% by weight of ethoxylated castor oil (10mol of ethylene oxide).

EXAMPLE 6

[0101] The emulsions prepared according to Examples 2-5 werecharacterized as follows.

[0102] Stability on Centrifugation.

[0103] The stability of the emulsions was evaluated by centrifugation.Two series of tests were carried out, the first with freshly preparedemulsions (t=0) and the second after storing the emulsions at roomtemperature for 24 hours (t=24 h).

[0104] A graduated test tube was filled with 15 ml of emulsion. The testtube was placed in a centrifuge running at 4000 revolutions/min (equalto 2525 g; g=gravity acceleration) for a total time of 30 min, at roomtemperature. The amount, expressed as % by volume, of water-rich phasewhich separated at the bottom of the test tube (creaming) was measuredat regular intervals of 5 minutes of centrifugation.

[0105] The results for the emulsions of Examples 2-5 are given in Table1.

[0106] Static Stability Under Temperature Cycle.

[0107] The storage stability of the emulsions was evaluated by thefollowing method.

[0108] A 1000 ml glass cylinder filled with the test emulsion was placedin a thermostatically-controlled oven whose temperature was controlledaccording to the following temperature cycle: 8 hours at 40° C., 8 hoursat 20° C., 8 hours at 5° C. The emulsion was subjected to thistemperature cycle for 14 days. 15 ml samples were then taken from thetop and the bottom of the emulsion, and were used to determine the watercontent by means of Karl-Fisher titration according to ISO standard3734. The same measurements were carried out on a sample subjected tothe temperature cycle for 28 days.

[0109] The results for the emulsions of Examples 2-5 are given in Table2 (values averaged over three samples).

[0110] As can be seen from the data given in Tables 1 and 2, theemulsions according to the invention shows high stability tocentrifugation and to the temperature cycles, whereas in the emulsionaccording to the prior art, the aqueous phase tends to settle in largeamounts.

[0111] Formation of Deposits on Metal Plate.

[0112] A stainless steel plate (10 cm×5 cm) was placed on a heatingplate maintained at a temperature of about 280-300° C. On reaching thistemperature, one drop of emulsion was placed on the steel plate every 30seconds, for a total of 10 drops. After depositing the final drop, theplate was cooled for a further 30 seconds. The formation of acarbonaceous deposit was observed on the plate. The test is to beconsidered as positive if this deposit can be easily wiped off in asubstantially complete manner by rubbing with a dry cloth, while thetest is negative if much of the deposit still sticks to the plate evenafter prolonged rubbing.

[0113] The test carried out with the emulsions according to theinvention (Ex. 2-4) gave a positive result, with formation of a thindeposit which was easily removed by rubbing. In contrast, thecomparative emulsion (Ex. 5) failed the test, since it formed a darkdeposit which could not be removed by rubbing.

[0114] Lubricity. Corrosion.

[0115] Compared with diesel fuel as such, the emulsion according to theinvention (Ex. 2-4) showed a lubricity (measured according to ISOstandard 12156/1) of about 270 μm, compared with a value of about 385 μmfor diesel fuel as such. Thus, the emulsion according to the inventionhas better anti-grip capacity than diesel fuel as such.

[0116] Evaluation of the corrosion according to standard EN590classified the emulsion according to the invention in Class la, equal tothat of diesel fuel as such. TABLE 1 Emulsion t = 0 Ex. 2 centrif. time5 10 15 20 25 30 (inv.) (min) creaming 0.50 1.10 1.75 2.32 2.60 3.02 (%vol) t = 24 h centrif. time 5 10 15 20 25 30 (min) creaming 0.50 0.811.51 1.76 2.24 2.70 (% vol) Emulsion t = 0 Ex. 3 centrif. time 5 10 1520 25 30 (inv.) (min) creaming 0.53 1.30 1.87 2.60 2.91 3.54 (% vol) t =24 h centrif. time 5 10 15 20 25 30 (mm) creaming 0.55 0.96 1.71 2.002.61 3.29 (% vol) Emulsion t = 0 Ex. 4 centrif. time 5 10 15 20 25 30(inv.) (min) creaming 0.40 0.90 1.67 12.12 2.39 2.86 (% vol) t = 24 hcentrif. time 5 10 15 20 25 30 (min) creaming 0.42 0.74 1.42 1.67 2.042.51 (% vol) Emulsion t = 0 Ex. 5 centrif. time 5 10 15 20 25 30 (comp.)(min) creaming 3.33 6.00 6.67 8.00 9.00 9.67 (% vol) t = 24 h centrif.time 5 10 15 20 25 30 (min) creaming 6.67 9.33 10.00 10.31 10.67 11.00(% vol)

[0117] TABLE 2 H₂O content H₂O content Time at the top at the bottomEmulsion (days) (% by weight) (% by weight) Ex. 2 0 11.54 (inv.) 1411.19 12.22 28 11.09 12.99 Ex. 3 0 11.56 (inv.) 14 11.05 12.26 28 11.0013.31 Ex. 4 0 11.62 (inv.) 14 11.33 12.24 28 11.23 12.67 Ex. 5 0 10.92(comp.) 14 6.06 42.31 28 1.74 62.46

1-39. (Canceled)
 40. A fuel comprising an emulsion between water and aliquid hydrocarbon, said emulsion being stabilized by at least oneemulsifier comprising a polymeric surfactant obtainable by: (a) reacting(i) at least one polyolefin oligomer functionalized with at least onegroup deriving from a dicarboxylic acid, or a derivative thereof; and(ii) at least one polyoxyalkylene comprising linear oxyalkylene units,said polyoxyalkylene being linked to a long-chain alkyl group optionallycontaining at least one ethylenic unsaturation; and (b) reacting theproduct of step (a) with (iii) at least one nitrogen compound selectedfrom monoamines, polyamines and quaternary ammonium hydroxides.
 41. Thefuel according to claim 40, wherein the polyolefin oligomer has anaverage molecular weight from 300 to 10,000.
 42. The fuel according toclaim 41, wherein the polyolefin oligomer has average molecular weightfrom 500 to 5,000.
 43. The fuel according to claim 40, wherein thepolyolefin oligomer derives from polymerization of mixtures of olefinshaving 4 carbon atoms, and mainly contains isobutene repeating units ofthe formula:


44. The fuel according to claim 40, wherein the polyoxyalkylenecomprises linear oxyalkylene units selected from —CH₂CH₂O—,—CH₂CH₂CH₂O—, —CH₂CH₂CH₂CH₂O—, or mixtures thereof.
 45. The fuelaccording to claim 44, wherein the polyoxyalkylene comprises from 2 to40 oxyethylene units of formula —CH₂CH₂O—.
 46. The fuel according toclaim 45, wherein the polyoxyethylene comprises from 5 to 20 oxyethyleneunits.
 47. The fuel according to claim 40, wherein the polyoxyalkyleneis a copolymer having from 2 to 30 oxyethylene units of formula—CH₂CH₂O—, and not more than 12 branched oxyethylene units of theformula:

wherein R is an alkyl having from 1 to 3 carbon atoms.
 48. The fuelaccording to claim 47, wherein R is methyl.
 49. The fuel according toclaim 40, wherein the polyoxyalkylene is linked to a long-chain alkylgroup of linear or branched structure, optionally containing at leastone ethylenic unsaturation, having from 8 to 24 carbon atoms.
 50. Thefuel according to claim 49, wherein the polyoxyalkylene is linked to thelong-chain alkyl group via an ester group.
 51. The fuel according toclaim 49, wherein the polyoxyalkylene is linked to the long-chain alkylgroup via an ether group.
 52. The fuel according to claim 40, whereinthe polyolefin oligomer is functionalized by reaction with adicarboxylic acid derivative selected from acyl halides, C₁-C₄ estersand anhydrides.
 53. The fuel according to claim 40, wherein thefunctionalized polyolefin oligomer is obtained by reaction betweenmaleic anhydride and a polyisobutene containing not less than 65% of exodouble bonds.
 54. The fuel according to claim 40, wherein the nitrogencompound (iii) is a primary, secondary or tertiary amine of the formula:

wherein R1, R2 and R3, equal or different from each other, are selectedfrom hydrogen; C₁-C₂₄ hydrocarbyl groups, optionally substituted with atleast one group selected from hydroxyl and C₁-C₄ alkoxy; R1 and R2 maybe linked to form a nitrogen-containing aliphatic heterocyclic ring,optionally containing at least one additional heteroatom; with theproviso that at least one of R1, R2 and R3 is different from hydrogen.55. The fuel according to claim 40, wherein the nitrogen compound (iii)is an alkylene polyamine of the formula:

wherein n is from 1 to 10; R4, R5 and R6, equal or different from eachother, are selected from hydrogen, alkyl or hydroxyl-substituted alkylgroup having from 1 to 30 carbon atoms, with the proviso that at leastone of R4 and R5 and at least one of R6 is hydrogen; and R7 is analkylene group having from 1 to 18 carbon atoms.
 56. The fuel accordingto claim 55, wherein R7 is an alkylene group having from 2 to 6 carbonatoms and/or n is from 2 to
 7. 57. The fuel according to claim 40,wherein the nitrogen compound (iii) is a quaternary ammonium hydroxideof the formula:

wherein R8, R9, R10 and R 11, equal or different from each other, areselected from C₁-C₂₄ hydrocarbyl groups, optionally substituted with atleast one group selected from hydroxyl and C₁-C₄ alkoxy; and R8 and R9may be linked to form a nitrogen-containing aliphatic heterocyclic ring,optionally containing at least one additional heteroatom.
 58. The fuelaccording to claim 40, wherein the polymeric surfactant is present in anamount from 0.1 to 5% by weight relative to the total weight of thefuel.
 59. The fuel according to claim 58, wherein the polymericsurfactant is present in an amount from 0.5 to 3% by weight relative tothe total weight of the fuel.
 60. The fuel according to claim 40,wherein the liquid hydrocarbon has a viscosity at 40° C. from 1 to 53cSt and a density at 15° C. from 0.75 to 1.1 kg/dm³.
 61. The fuelaccording to claim 40, wherein the water is present in an amount from 3to 40% by weight relative to the total weight of the fuel.
 62. The fuelaccording to claim 61, wherein the water is present in an amount from 7to 20% by weight relative to the total weight of the fuel.
 63. The fuelaccording to claim 40, further comprising at least one cetane improver.64. The fuel according to claim 63, wherein said at least one cetaneimprover is selected from inorganic nitrates, inorganic nitrites andinorganic peroxides.
 65. The fuel according to claim 63, wherein said atleast one cetane improver is selected from organic nitrates, organicnitrites and organic peroxides.
 66. The fuel according to claim 40,further comprising at least one biocide.
 67. The fuel according to claim40, further comprising at least one alcohol.
 68. The fuel according toclaim 67, wherein the alcohol is selected from methanol, ethanol,isopropanol and glycols, or mixtures thereof.
 69. The fuel according toclaim 67, wherein the alcohol is present in an amount from 0.5 to 8% byweight relative to the total weight of the fuel.
 70. The fuel accordingto claim 69, wherein the alcohol is present in an amount from 1 to 4% byweight relative to the total weight of the fuel.
 71. A process forfueling a combustion apparatus comprising at least one combustionchamber, comprising: feeding a fuel to said at least one combustionchamber; igniting said fuel in said at least one combustion chamber;wherein said fuel comprises an emulsion between water and a liquidhydrocarbon said emulsion being stabilized by at least one emulsifiercomprising a polymeric surfactant obtainable by: (a) reacting (i) atleast one polyolefin oligomer functionalized with at least one groupderiving from a dicarboxylic acid, or a derivative thereof; and (ii) atleast one polyoxyalkylene comprising linear oxyalkylene units, saidpolyoxyalkylene being linked to a long-chain alkyl group optionallycontaining at least one ethylenic unsaturation; and (b) reacting theproduct of step (a) with (iii) at least one nitrogen compound selectedfrom: monoamines, polyamines and quaternary ammonium hydroxides.
 72. Theprocess according to claim 71, wherein said combustion apparatus is aninternal combustion engine.
 73. A polymeric surfactant obtainable by:(a) reacting (i) at least one polyolefin oligomer functionalized with atleast one group deriving from a dicarboxylic acid, or a derivativethereof; and (ii) at least one polyoxyalkylene comprising linearoxyalkylene units, said polyoxyalkylene being linked to a long-chainalkyl group optionally containing at least one ethylenic unsaturation;and (b) reacting the product of step (a) with (iii) at least onenitrogen compound selected from monoamines, polyamines and quaternaryammonium hydroxides.
 74. The polymeric surfactant according to claim 73,wherein the polyolefin oligomer has an average molecular weight from 300to 10,000.
 75. The polymeric surfactant according to claim 73, whereinthe polyolefin oligomer derives from the polymerization of mixtures ofolefins having 4 carbon atoms, and mainly contains isobutene repeatingunits of the formula:


76. The polymeric surfactant according to claim 73, wherein thepolyoxyalkylene, comprises linear oxyalkylene units selected from—CH₂CH₂O—, —CH₂CH₂CH₂O—, —CH₂CH₂CH₂CH₂O—, or mixtures thereof.
 77. Thepolymeric surfactant according to claim 76, wherein the polyoxyalkylenecomprises 2 to 40 oxyethylene units of the formula —CH₂CH₂O—.
 78. Thepolymeric surfactant according to claim 77, wherein the polyoxyethylenecomprises from 5 to 20 oxyethylene units.
 79. The polymeric surfactantaccording to claim 73, wherein the polyoxyalkylene is a copolymer havingfrom 2 to 30 oxyethylene units of the formula —CH₂CH₂O—, and not morethan 12 branched oxyethylene units of the formula:

wherein R is an alkyl having from 1 to 3 carbon atoms.
 80. The polymericsurfactant according to claim 73, wherein the polyoxyalkylene is linkedto a long-chain alkyl group, of linear or branched structure, optionallycontaining at least one ethylenic unsaturation, having from 8 to 24carbon atoms.
 81. The polymeric surfactant according to claim 80,wherein the polyoxyalkylene is linked to the long-chain alkyl group viaan ester group.
 82. The polymeric surfactant according to claim 80,wherein the polyoxyalkylene is linked to the long-chain alkyl group viaan ether group.
 83. The polymeric surfactant according to claim 73,wherein the polyolefin oligomer is functionalized by reaction with adicarboxylic acid derivative selected from acyl halides, C₁-C₄ estersand anhydrides.
 84. The polymeric surfactant according to claim 73,wherein the functionalized polyolefin oligomer is obtained by reactionbetween maleic anhydride and a polyisobutene containing not less than65% of exo double bonds.
 85. The polymeric surfactant according to claim73, wherein the nitrogen compound (iii) is a primary, secondary ortertiary amine of the formula:

wherein R1, R2 and R3, equal or different from each other, are selectedfrom hydrogen; C₁-C₂₄ hydrocarbyl groups, optionally substituted with atleast one group selected from hydroxy and C₁-C₄ alkoxy; R1 and R2 may belinked to form a nitrogen-containing aliphatic heterocyclic ring,optionally containing at least one additional heteroatom; with theproviso that at least one of R1, R2 and R3 is different from hydrogen.86. The polymeric surfactant according to claim 73, wherein the nitrogencompound (iii) is an alkylene polyamine of the formula:

wherein n is from 1 to 10; R4, R5 and R6, equal or different from eachother, are selected from hydrogen, alkyl or hydroxyl-substituted alkylgroups having from 1 to 30 carbon atoms, with the proviso that at leastone of R4 and R5 and at least one of R6 is hydrogen; and R7 is analkylene group having from 1 to 18 carbon atoms.
 87. The polymericsurfactant according to claim 73, wherein the nitrogen compound (iii) isa quaternary ammonium hydroxide of the formula:

wherein: R8, R9, R10 and R11, equal or different from each other, areselected from C₁-C₂₄ hydrocarbyl groups, optionally substituted with atleast one group selected from hydroxyl and C₁-C₄ alkoxy; R8 and R9 maybe linked to form a nitrogen-containing aliphatic heterocyclic ring,optionally containing at least one additional heteroatom.